USB 2.0 (2) – Model B of the Raspberry Pi has two USB plugs. In the beginning you might just use the USB plugs for a keyboard and mouse. Later on you might find that a USB hub is necessary for port expansion to support a USB drive or a USB wifi device.

SD card – Up to 32GB SD Cards have been tested and found to work with the Raspberry Pi. Adafruit sells a 4GB card.

HDMI (v1.3a) – This will be used for video output connected to modern TVs, monitors and projectors. It can also supports audio over HDMI. If you do not have a HDMI ready display a inexpensive ($2) HDMI to DVI adapter can be obtained. Converting HDMI to VGA would be expensive and lossy.

RCA Video – Connects to old school NTSC / Pal TVs for output. If you can’t make it work with a digital HDMI connector try this plug.

3.5mm Stereo Plug – This is the audio out jack. When connecting to a TV or amplifier you may use a 3.5mm to dual RCA (white/red) stereo plug. If you need audio in a USB mic can be used.

USB mini plug – This port powers the raspberry pi. There is no on or off switch just remove the power when you want to shut it off. It has a hefty 700mA @ 5V requirement which mean you will want to pickup a power supply and a USB A –> Micro B cable. If portability is critical this unit could run off 4xAAs.

Ethernet – Model B includes ethernet support for 10/100 MB. It does not include power over ethernet at this time, although it is being considered.

Expansion Header – 26 pins have been broken out from the Raspberry Pi in a 2×13 grid. The pins include 8 GPIOS, a UART, SPI, and I2C. A ribbon cable can be connected to breakout boards and breadboard adapters to simplify working with the raspi. These pins are what you will use to turn work with LEDs, relays, serial consoles and anything you might have done with a Arduino. It’s important to note that these pins are not 5V tolerant. You must level shift the voltage to 3.3v. Note: the kernel outputs during boot at 115200bps to the UART.

Camera Plug CSI – Still somewhat experimental the connectors for the CSI ports were not included on all models. The idea here is that the type of cameras used in cell phones could be plugged in and used with the raspi. There is a lot of discussion in the forums including photos taken by working CSI cameras that have been plugged in. At the time of this writing nobody is shipping a header board or camera which can plug directly into the CSI connector.

Video Plug DSI – The DSI is another somewhat experimental connector which was not populated on all models. The Display Serial Interface makes use of a 15-way flat flex connector. The idea is that you could have dual displays and interface with the kind of raw LCDs used in cell phones (including touch screens). I was unable to locate any reports of successful use of the DSI plug.

It is also important to remember that the USB ports can only source 140mA of current each due to the fuses on them. This means no WiFi adapters can be plugged directly into the Pi– hub only. Also, the whole board is limited to 700mA current draw from the MicroUSB power jack (which you have labeled as a usb *mini* plug).